1. Field of the Invention
The present invention relates to a device and a system for message processing for transferring messages among vehicles.
2. Description of the Related Art
Common networks such as the Internet need server equipment for administering formation, retention, and destruction of communication channels, as well as for relaying and temporarily storing data. However, in the case where information is obtained from a vehicle passing through a certain zone, and information is conveyed to a vehicle passing through a certain zone, the information is not always useful for the drivers in the vehicles. Therefore, asking the drivers to bear the communication costs and costs for network operation and maintenance is sometimes difficult.
A method for creating a message including a vehicle position next to a header is recognized as a known technology for easily transmitting and receiving messages between vehicles. With regard to this technology, Japanese Unexamined Patent Application No. 2002-190093 is incorporated herein by reference. A message including position data of a vehicle transmitting the message allows the location from which the message is transmitted to be identified. Thus, in the above case of obtaining information from a vehicle passing through a certain zone using this kind of message, the method has an advantage of allowing a receiving device to check whether or not the location from which the message is transmitted is within a certain zone.
In the above-mentioned Japanese Patent Application, the message is assumed to be received and transmitted between vehicles only. Thus, it is disadvantageous if dedicated equipment, such as a server for administering formation, retention, and destruction of communication channels, is required to transmit or receive a message between vehicles whose radio waves cannot reach one another. Especially, if the message is transmitted or received between vehicles whose radio waves cannot reach one another without such a server, the message must be transferred through another vehicle between these vehicles. This has the drawback of remaining old messages.